1. Field of the Invention
The present invention relates to a piano sound source apparatus for outputting a composite tone using a piano sound source providing a plurality of sinusoidal oscillation frequencies and a method and program for piano sound synthesis.
2. Description of the Related Art
FIG. 8 shows a known piano sound source apparatus. Referring to FIG. 8, in the known piano sound source apparatus, an oscillator 82-1 generates a sine wave corresponding to a fundamental tone using data 81-1 regarding frequency, amplitude, and time variation. In addition, an oscillator 82-N generates a sine wave corresponding to an Nth harmonic using data 81-N regarding frequency, amplitude, and time variation. Further, a noise generator 83 generates a signal corresponding to noise.
An adder 84 adds sine waves, corresponding to the fundamental tone and respective harmonics up to the Nth harmonic, generated by the oscillators 82-1 and 82-N and the signal, corresponding to the noise, generated by the noise generator 83 and outputs the resultant tone as a composite tone. In other words, the adder 84 outputs the composite tone obtained by adding all of the sine waves of the fundamental tone and the respective harmonics up to the Nth harmonic and the noise.
Further, a low-pass filter 86 changes its cut-off frequency in accordance with data 85 about the intensity of a musical performance tone and passes the composite tone obtained by adding all of the sine wave of the fundamental tone and the respective harmonics up to the Nth harmonic and the noise. After that, an attenuator 87 controls the amplitude of the composite tone in accordance with the data 85 and outputs the resultant tone as a composite tone 88.
The above-described cut-off frequency control and attenuation on the composite tone according to the intensity of the tone are based on the fact that general piano tones have such properties that high-order harmonics and noise are reduced when the intensity of a musical performance tone is low.
Japanese Unexamined Patent Application Publication No. 10-247084 discloses a sound source apparatus for slightly changing a timbre according to timbre control information generated on the basis of a key touch and other factors. The apparatus includes an arithmetic unit in each of oscillators similar to the above-described oscillators 82-1 to 82-N. In the apparatus, a band waveform signal is generated on the basis of frequency data and the result of calculation obtained using a coefficient by each arithmetic unit, the coefficient being determined according to two or more timbre control parameters for control of a timbre.